Pencil compass



March 26, 1963 A. AUGUSTIN 3,082,533

PENCIL COMPASS Original Filed Feb. 17, 1960 BY A United States Patent 1Claim. (Cl. 33-27) The present invention relates generally to compassesand specifically to an improved pencil clamp for use in conjunction witha pencil compass.

This application is a division of my earlier filed application, SerialNo. 9,243, filed February 17, 1960 and entitled Compass Pencil Clamp.

The use of a compass to draw a circle or a portion of an arc is wellknown in the art and a large variety of differing compasses have beenproduced. The present invention is concerned specifically with that typeof compass which employs the use of a pencil to describe the are orcircle produced. The pencil compass is a relatively inexpensive item andis generally designed for mass production manufacture and low sellingprice. A persistent problem which has existed in the manufacture ofpencil compasses has been the difiiculty in producing a mechanism whichwill easily and accurately clamp a pencil within the compass and at thesame time, be relatively inexpensive to manufacture. Included within thedisadvantages of the prior art clamps for pencil compasses has been thegeneral failure to solve the problem connected with the requirement foreasy removal of the pencil for sharpening, the accurate adjustment ofthe pencil relative to the compass as the pencil point becomes worn anda clamping of a pencil within the pencil compass without damaging thepencil.

Generally, it is an object of the present invention to provide a pencilclamp for use in a pencil compass which eliminates the disadvantages ofthe prior art pencil clamps as described above. Specifically it is anobject of the present invention to provide a pencil clamp which willfirmly secure a pencil to one leg of a compass and which will allow foreasy positioning of the pencil.

A further object of the present invention is to provide a pencil clampwhich will not mar the surface of a pencil contained therein.

It is still a further object of the present invention to provide apencil clamp which is relatively easy to manufacture in mass productiontechniques and which effectively clamps a pencil such that its positionwithin the clamp may be adjusted.

In accordance with one illustrative embodiment of the present inventionthere is provided a conventional pencil compass which incorporates, asan integral part of one of its legs, an improved pencil clamp. Thepencil clamp comprises a cylindrical band having a longitudinal slittherein and including two integrally formed ears on opposite sides ofsaid longitudinal slit. Releasable clamping means are provided andincludes a slide having converging camming walls which are providedabout the protruding cars such that relative movement between the slideand the ears is effective to draw the ears together. This action isefiective to decrease the internal diameter of the cylindrical band and,thereby, clamp a pencil within the clamp.

The above brief description as well as further objects, features andadvantages of the present invention will be best appreciated byreference to the following detailed description of a presently preferredembodiment, when taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a side elevational view of a pencil compass Patented Mar. 26,1963 a ICC incorporating a pencil holder according to the presentinvention;

FIG. 2 is an enlarged fragmentary view of the pencil clamp shown in FIG.1, the clamp being illustrated in its clamping position;

FIG. 3 is a view similar to FIG. 2 with the clamp being illustrated inits opened position; and,

FIG. 4 is a sectional view taken along the lines 4-4 of FIG. 2. andlooking in the direction of the arrows.

Referring now specifically to the drawings, there is shown in FIG. 1 apencil compass, generally labelled by the numeral 100, incorporating apencil holder or clamp generally designated by the numeral 112. The.pencil compass is of conventional structure and is com prised of twolegs 114 and 116, which are pivotally joined at their upper ends by thepivot rivet 118-. Frictional clamping forces are provided between thetwo legs 114, 116 by the pivot rivet 118, spring washers 1 20, and thecenter plate 122 which has a center post 124. The pivot rivet 118, thespring washer 120, the center plate 122 and the legs 114, 116 areassembled in a manner which is well known to those skilled in the art,such that the center post I124 always bisects the angle between the legs114, 116. The leg 114 has attached to its lower portion a pointed member126 about which the compass is pivoted when in use. The other leg 116has an arcuate extension 28 which extends inwardly towards the leg 114and extends beyond the leg 114. The arcuate extension 128 serves as anindex of the radius of the are described by the compass. A scale 130,inscribed on the extension 128 coats with the index marker 132 on theleg 114 to provide this reading. In use, the operator of the pencilcompass 100 places the pointed member 126 at the center of an arc to beformed and with the pencil P which is supported in the holder 112 and hedescribes an are about the point of member 126.

The pencil holder, best seen in FIGS. 3 and 4, consists of a cylindricalband 134 which has an internal diameter approximately equal to thediameter of the pencil P. The band 134 has an opening or slit 136 whichruns the length of the band 134 and has two juxtaposed side edges 138,140 which define the width of the opening 136. The cylindrical band 134is constructed of a flexible material, such that the Width of the slit136 may be elastically varied. It will be appreciated that upon adecrease of the width of the slit 136 by a movement of the side edges138, 140 towards each other, the internal diameter of the cylindricalband 134 will be decreased thereby positively gripping a pencil Pdisposed therein.

Clamping mechanisms 142 are provided to accomplish this result. Theclamping mechanisms 142 consist of a pair of ears 144, 146 which extendoutwardly from the cylindrical band 134 at opposing points along theedges 138, 140 respectively of the opening 136. The ears 144, 146 arebent away from the opening 136 and are folded partially back against thecylindrical band 134. A slide 148 is provided with converging cammingwalls 152, 154 which define an opening 150 contained therein. As may beseen in FIGS. 2 and 3, the converging camming walls 152, 154 are closertogether at the upper end of the slide 148 than at the lower endthereof. The clamping ears 144, 146 are contained within the opening 150and are engaged in abutting relationship with the respective cammingwalls '152, 154. It will thus be appreciated that when the slide 148 ismoved downwardly relatively to the ears 144, 146 the opening 136 will benarrowed by the camming action of the camming walls 152, 154 on the ears144, 146 respectively, and thus, the internal diameter of thecylindrical band 134 will be reduced into a clamping position. The clamp112 is pictured in its clamping position in FIG. 2. A finger tab 156 isproa 3 vided on the upper end of the slide-148 to facilitate themovement of the slide 148 relative to the ears 144, 146. When the slide148 is moved from the position shown in FIG. 2 to the position shown inFlG. 3, i.e., moved up wardly relative to the ears 144, 146', the ears144, 146 will be engaged in the lower portion of the slide 148 whereinthe camming Walls 152, 154 are spaced relatively far from each other.Thus, the clamping ears 144, 146 will be allowed to spread apart andthus increase the diameter of the cylindrical band 134. When a pencil Phas been placed in the desired position relative to the holder or clamp112 as seen in FIG. 3, the operator moves the slide 143 by means of thefinger tab.156 downwardly relative to the ears 144, 146 thusvcammi'ngthem towards each other by the action of the camming walls 152, 154.

It will be appreciated that the present invention provides easilyoperative and effective clamping means to retain a pencil within apencil compass. A simple camming device is utilized to decrease thewidth of an opening in a cylindrical band, the cylindrical band beingapproximately the diameter of a pencil. When the sides of the openingare drawn together, the pencil is clamped within the cylindrical'band.Positioning of the pencil with respect to the band is relatively simpleand the device itself is both dependable and relatively inexpensive tomanufacture.

A latitude of modification, substitution and change is intended in theforegoing disclosure and in some instances some features of theinvention will be used without a use of other corresponding features.Accordingly, the claims herein should be construed broadly and in amanner consistent with the spirit and scope of the invention.

What I claim is: a

A pencil holder for use with a two legged pencil compass comprising astamped one piece resilient cylindrical band integrally formed withoneof the legs of said pencil compass, said cylindrical band having alongitudinal slit formed therein having spaced parallel edges extendingthe length of said band, said band being resiliently deformable betweena normal position wherein the diameter of the band is slightly largerthan the diameter of a pencil to be held within said band and a clampingposition wherein the parallel edges of said slit are drawn together andthe diameter of said band is reduced, a pair of cars extending outwardlyfrom said band at points at substantially the middle of said paralleledges, said ears being integral extensions of the material of said bandand said leg, and releasable clamping means comprising a slide platehaving a central cut-out having a pair of converging camming edges onopposite sides of said cut-out, said slide plate being in cooperatingengagement. with said ears with said ears extending through said cut-outand engaged against said converging camming edges, said slide platebeing movable longitudinally through a prescribed stroke for moving saidcamrning edges with respect to said ears to draw said ears together andthereby to resiliently deform said'band into said clamping position atone end of the stroke and torelease said ears for movement away fromeach other to allow said band to assume its normal, non-clampingposition, said ears being substantially smaller in the longitudinaldirection than said slide plate to allow said slide plate to be movedthrough said longitudinal stroke.

References Cited in the file of this patent UNITED STATES PATENTS

